Impact of Land Cover Change on Flood Runoff Characteristics of the Headwater Sub-Catchments in the Nyando River Basin, Kenya
The effects of land cover change on runoff characteristics of four sub-catchments located in the headwaters of the Nyando River Basin (3500 km2) of Kenya were simulated in this study. Land cover change data were obtained by classifying Landsat satellite images based on six major land cover classes prevalent in the basin. The accuracy of the classifications was assessed with the help of reference datasets acquired from the FAO-Africover land cover dataset and digitized topographic maps (1:50 000) of the basin. The mapped land cover data, together with a DEM and a digital soil map, were used to estimate the parameters for parsimonious conceptual rainfall-runoff models, namely the Natural Resource Conservation Service-Curve Number (NRCS-CN) and Clarks Unit Hydrograph (C-UH) used to generate and transform runoff from a typical rainfall storm characteristic of the basin. Land cover classification results obtained revealed that, over the study period, forest cover declined by 20% while agricultural fields expanded by 16%. The headwater sub-catchment with the highest reduction in forest coverage exhibited the highest simulated change in runoff, leading to increased runoff volumes and peak discharges by up to 22%. Generally, simulated runoff peak discharges were noted to have increased in the study sub-catchments by factors of 1.1 to 1.22 over the study period.
| Main Authors: | , , , |
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| Format: | Report Section biblioteca |
| Language: | English |
| Published: |
UNESCO
2009
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| Subjects: | Satellite sensing, Rainfall, Rain, Runoff, Models, Catchment area, |
| Online Access: | http://hdl.handle.net/1834/7035 |
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